A torque converter to crankshaft assembly includes a transmission torque converter and an engine crankshaft. The torque converter may have an axially extending pilot with an outer end and a conical surface spaced inward from the outer end. A radial drive plate is bolted to the crankshaft and to mounting bosses on the face of the torque converter to carry drive torques between the engine and torque converter. The crankshaft has a recess for receiving the outer end of the pilot, and a conical chamfer surface at an outer end of the recess to engage the conical surface of the pilot.
Two methods of assembling a torque converter to a crankshaft are commonly used. One method is applied to a butt joint pilot converter. This method involves inserting the pilot of the torque converter into the recess of the crankshaft until the conical surface of the pilot directly engages the conical surface of the chamfer. During assembly, the contact between the conical surface of the pilot and the chamfer provides the alignment that centers the torque converter relative to the crankshaft. During engine operation, as the torque converter balloons, the conical surface of the torque converter pilot applies axial thrust on the crankshaft, requiring the engine to have high strength crankshaft thrust bearings to deal with the direct and indirect thrust loads created by the ballooning of the torque converter.
The second method is applied to a floating joint pilot converter. This involves inserting the pilot of the torque converter within the recess of the crankshaft so that the conical surface of the pilot is spaced axially from the conical surface of the chamfer. During assembly, the chamfer surface and the conical surface do not engage to center the torque converter within the crankshaft. As a result, the alignment by this method varies because of required clearances and tolerances. During engine operation, the clearance between the crankshaft and the torque converter provides expansion room for torque converter ballooning. As a result, the engine can use standard crankshaft thrust bearings to deal with indirect thrust loads of the torque converter.
A torque converter to crankshaft assembly having the installation benefits of a butt joint pilot converter and the expansion benefits of floating joint pilot converter is desired.